Hi,
I'm having some difficulties finding the correct transistor. I'm designing a inductorless and transformerless RF power amplifier at
40Mhz, 1 Watt output. The design is somewhat different I guess. There is no impedance matching and I'm trying to maximise linearity and bandwidth. I'm operating on a 24V supply. I currently have a common- base stage, feeding into a shunt-feedback stage (gain) then onto a push-pull power amplifier.I'm having trouble finding a relatively cheap option for the power stage. RF Power Transistors are generally too expensive and hard to obtain. Darlington are good but the poor Ft is a problem. Philips (NXP) have alot of good RF BJTs but the 24V supply really seems to limit my options. It seems I'm trying to find a transistor which isn't quite small-signal and isn't quite power, something in between. I've had a look at the older Motorola and NXP transistors and they would have been perfect, but these medium voltage, RF transistors seems to gone; replaced by small-signal RF.
Any help would be great.
Regards, Alan.